2021 yz 450 engine failure ?

DirtRoadmx47
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DirtRoadmx47
Edited Date/Time 5/26/2021 6:24am
Friends 30 hour 2021 yz 450 engine suffered catastrophic engine failure on first lap ? well maintained stock bike ? anybody have this happen to their 21 yz 450 ?
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mattyhamz2
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mattyhamz2 5/17/2021 7:59am
5/17/2021 7:59am
I mean this with no offense, but I've seen some pretty clapped out "well maintained" bikes with 15-30 hours on them...

Is your friend the original owner of the bike? Or did he buy it used with "30 hours" and it blew up on his first lap?
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DirtRoadmx47
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DirtRoadmx47 5/17/2021 8:16am
5/17/2021 8:16am
No offense taken, Was a trade at 15 hours but no engine work, Just looking for some possible answers, Don't know if you could find the reason looking at the damaged motor ?
PDUB481
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PDUB481 5/17/2021 8:21am
5/17/2021 8:21am
It wasn't a engine failure, it was a maintenance failure
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TheGetFresh
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TheGetFresh 5/17/2021 8:21am
5/17/2021 8:21am
DirtRoadmx47 wrote:
No offense taken, Was a trade at 15 hours but no engine work, Just looking for some possible answers, Don't know if you could find the...
No offense taken, Was a trade at 15 hours but no engine work, Just looking for some possible answers, Don't know if you could find the reason looking at the damaged motor ?
I mean... that’s probably a better place to start than vital.
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Moto520
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Moto520 5/17/2021 9:10am
5/17/2021 9:10am
I don't know but these bikes are as bulletproof as any bike i've ever owned. It's very critical to take care of the air filter properly and i could see a youngster doing this incorrectly. It's easy once you get it down but leaves room for error.
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mattyhamz2
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mattyhamz2 5/17/2021 9:50am
5/17/2021 9:50am
DirtRoadmx47 wrote:
No offense taken, Was a trade at 15 hours but no engine work, Just looking for some possible answers, Don't know if you could find the...
No offense taken, Was a trade at 15 hours but no engine work, Just looking for some possible answers, Don't know if you could find the reason looking at the damaged motor ?
My opinion...

With everything going on right now the previous owner could have bought it as a first bike which ended up being too much to handle, didn't maintain it properly, probably dropped dirt into the intake(because the YZF filter system isn't exactly beginner/low knowledge friendly) which went through the motor and caused the issue.

or could have been a weird freak issue.
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SilverSpurs
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SilverSpurs 5/17/2021 9:59am
5/17/2021 9:59am
Dumgeon time.

Probably run with no oil or the filter in backwards.
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yz133rider
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yz133rider 5/17/2021 10:00am
5/17/2021 10:00am
SilverSpurs wrote:
Dumgeon time.

Probably run with no oil or the filter in backwards.
They aren’t all perfect from the factory. Things happen.
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LungButter
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LungButter 5/17/2021 10:00am
5/17/2021 10:00am
SilverSpurs wrote:
Dumgeon time.

Probably run with no oil or the filter in backwards.
What's a Dumgeon?

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mtl
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mtl 5/17/2021 11:45am
5/17/2021 11:45am
I'd start working backwards from "first lap".

What changed between the last time ridden and this time?
Timo
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Timo 5/17/2021 11:56am
5/17/2021 11:56am
What does catastrophic engine failure entail? Rod break and knock a hole through the cases? Valve failure, piston seizure, crank bearing seizure, camshaft bearing seizure... More info needed.
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JM485
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JM485 5/17/2021 12:30pm
5/17/2021 12:30pm
It‘a a little hard to diagnose a problem with zero pictures, no explanation, and almost no context about the bike.
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Yeti831
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Yeti831 5/17/2021 3:13pm
5/17/2021 3:13pm
1) Elaborate on “Failure”. What happened when riding in what gear and what did it do?

2) post pictures if inside parts are trying to be outside parts

3) if not, tear it down to the cases and post pictures of what looks done-zo
Blue Groove 5/17/2021 4:52pm
5/17/2021 4:52pm Edited Date/Time 5/17/2021 4:53pm
How long until a .... "If it was a KTM they would cover the repair, my buddy had one covered at 60hrs, because they really know how to take care of their customers!"??

Sucks for the guy but every brand has failures even with perfect maintenance. Backwards oil filters do happen too, especially in a first lap scenario if it was just serviced. Not sure how easy to do on a Yamaha though.
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DirtRoadmx47
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DirtRoadmx47 5/17/2021 5:35pm
5/17/2021 5:35pm Edited Date/Time 5/17/2021 5:39pm
End of the connecting rod on piston wrist pin broke off, valves not bent,cam lobes not marred and in good shape. Yamaha and dealer working with customer.
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tzmike
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tzmike 5/18/2021 6:59am
5/18/2021 6:59am
A 21 that over heated. Took off head and piston was CRACKED along wrist pin. No compression.
20 hrs on bike. Also zero coolant loss.
SMFH.....
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McG194
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McG194 5/18/2021 7:25am
5/18/2021 7:25am
What is "Catastrophic engine failure"?

There are a lot of things that could be considered catastrophic from valves to crank. .
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mx317
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mx317 5/18/2021 7:33am
5/18/2021 7:33am Edited Date/Time 5/18/2021 7:33am
McG194 wrote:
What is "Catastrophic engine failure"?

There are a lot of things that could be considered catastrophic from valves to crank. .
He answered two posts above. End of connecting rod broke off.
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GeorgiePorgie 5/18/2021 7:49am
5/18/2021 7:49am
PDUB481 wrote:
It wasn't a engine failure, it was a maintenance failure
Everything mechanical fails at some point....

Sucks you’re the second owner.....open her up and let’s see what happened.
Richy
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Richy 5/18/2021 8:04am
5/18/2021 8:04am
Bad times, hope it's no more grief than it needs to be.

Just to be clear, we're talking the rod itself failed, not the piston cracked in that area or a circlip got away and the wrist pin shuffled across or something?
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Camp332
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Camp332 5/18/2021 8:06am
5/18/2021 8:06am
Best answer I got is, he probably doesn't even lift Bro.
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Timo
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Timo 5/18/2021 5:32pm
5/18/2021 5:32pm
Probably defective rod, be glad it didn't get pushed through the cases and rebuild. #racebikes
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Brent
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Brent 5/18/2021 6:56pm
5/18/2021 6:56pm
"WAIT- engine oil needs to be changed?"

...said my ex wife when her Suburban blew up after 60K miles on the original oil....


LaughingLaughingLaughingLaughingLaughingTongue
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Vet57
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Vet57 5/19/2021 3:56am
5/19/2021 3:56am
Camp332 wrote:
Best answer I got is, he probably doesn't even lift Bro.
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ben5020
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ben5020 5/19/2021 8:46am
5/19/2021 8:46am
PDUB481 wrote:
It wasn't a engine failure, it was a maintenance failure
There is no way a bike that costs over 10k otd should blow up at 30 hours.
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Leeham
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Leeham 5/19/2021 10:37am
5/19/2021 10:37am
ben5020 wrote:
There is no way a bike that costs over 10k otd should blow up at 30 hours.
Run it on old oil/filter for 30 hours. Who knows what happened. Sometimes freak incidents happen. On these Yamahas where they only hold around .75-.8 liters of oil, oil gets used up pretty quick!
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